The invention relates in general to the arrangement and use of radio frequency identification (RFID) tags. In particular, the inventions relate to programming a value on an RFID tag using mechanically alterable elements of the tag.
Radio frequency identification (RFID) tags are electronic devices that may be affixed to items whose presence is to be detected and/or monitored. RFID tags are classified based on standards defined by national and international standards bodies (e.g., EPCGlobal and ISO). Standard tag classes include Class 0, Class 1, and Class 1 Generation 2 (referred to herein as “Gen 2”). The presence of an RFID tag, and therefore the presence of the item to which the tag is affixed, may be checked and monitored wirelessly by an “RFID reader”, also known as a “reader-interrogator”, “interrogator”, or simply “reader.” Readers typically have one or more antennas for transmitting radio frequency signals to RFID tags and receiving responses from them. An RFID tag within range of a reader-transmitted signal responds with a signal including a unique identifier.
With the maturation of RFID technology, efficient communication between tags and readers has become a key enabler in supply chain management, especially in manufacturing, shipping, and retail industries, as well as in building security installations, healthcare facilities, libraries, airports, warehouses etc. Many processes, as well as the status of many items, may be readily monitored via RFID tags
RFID tags have been developed where, by means of mechanical alterations to a tag (such as, for example, by severing or completing an external circuit path associated with the tag), it is possible to modify an internal data state of the tag. In this way, an RFID tag may be used to report on a mechanically changed state or other condition of items with which a tag is associated. For example, an RFID tag attached to a container of medicine may be used to monitor, and to report on, whether the container has been tampered with, or whether the cap has been removed. Similarly, RFID tags may be used to report on markings made on a written sheet, provided the conductivity of the sheet is altered in the process of marking the sheet, and provided a circuit path associated with the RFID tag is thereby modified as well.
In general then, there have been uses of RFID tags where mechanical, “off-chip”, modifications to a circuit path have been employed to modify a data state of a tag, and so modify the data reported by the tag. Generally, however, custom RFID tags and custom off-chip or custom off-tag mechanisms have been employed for these purposes. There has been no general-purpose, off-the-shelf, mechanically-programmable RFID tag, usable in a wide variety of contexts and applications as new needs arise, which can be easily used to generically monitor items or processes as changes occur.
What is needed, then, is an RFID tag which can be easily mechanically modified to indicate and report changes in data states, and which can further be easily applied to and integrated into diverse contexts for item/process monitoring and reporting purposes.